Rotary pumps and engines are machines which have rotary elements which do work. Rotary engines include a piston which rotates in a cylinder to convert energy into mechanical force or motion. Rotary pumps include a pair of members in rotational contact to draw a fluid therein through an inlet port and force the fluid out through an exhaust port.
One well-known type of rotary engine is the Wankel engine which comprises a rotary-type internal combustion engine having a rotor and an eccentric shaft. The rotor moves in one direction around a trochoidal chamber containing peripheral inlet and exhaust ports. The rotor divides the chamber volume into three compartments.